Bighead Searobin, Prionotus tribulus

Bighead Searobin, Prionotus tribulus. Fish caught from coastal waters off West Palm Beach, Florida, November 2023. Length: 5.1 cm (2.0 inches). Catch, photograph and identification courtesy of James Lafontaine, Long Island, New York.

Bighead Searobin, Prionotus tribulus. Fish caught from coastal waters off Tampa, Florida, May 2018. Length: 11.5 cm (4.5 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.

Bighead Searobin, Prionotus tribulus. Fish caught from coastal waters of the Passe-A-Grille Marina, St. Petersburg, Florida, August 2014. Length: 11.5 cm (4.5 inches). Catch, photograph and identification courtesy of Ryan Crutchfield, Tampa, Florida.

Bighead Searobin, Prionotus tribulus. Fish caught from the Indian River Lagoon, Fort Pierce, Florida, March 2023. Length 15 cm (5.9 inches). Catch, photograph and identification courtesy of Doug Bomeisler, Fort Pierce, Florida.

Bighead Searobin, Prionotus tribulus. Fish caught from within the Biloxi Bay, Biloxi, Mississippi, June 2023. Length 15 cm (5.9 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.

Bighead Searobin, Prionotus tribulus. Fish caught from coastal waters off Charleston, South Carolina, December 2020. Length: 20 cm (7.9 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.

The Bighead Searobin, Prionotus tribulus, is a member of the Searobin or Triglidae Family, that is also known as the Flying Gurnard, and in Mexico as rubio cabezón. Globally, there are twenty-three species in the genus Prionotus, of which fifteen are found in Mexican waters, ten in the Atlantic and five in the Pacific Ocean.

The Bighead Searobin has an elongated slim body. They are brown to gray-brown dorsally transitioning to white or yellowish-white ventrally. They have three short oblique bars on the upper body, a transparent caudal fin with a wide darker bar near the tip, a large dark blotch between dorsal spines 3 and 4, transparent pelvic fins, brown pectoral fins with cross bars with green on the lower margins and the free rays are barred. Their head is large, deep and long being greater than one-third the standard length that does not have cirri, with a large mouth that reaches the eyes and opens slightly under the snout, and long prominent preopercular spine. Their anal fin has 10 rays; their caudal fin is square; their dorsal fin has 10 spines and 12 rays; and, their pectoral fins are large with 13 or 14 rays with the first 3 being are enlarged and free-standing. They have 8 to 16 gill rakers. Their body is covered with small scales.

The Bighead Searobin is a demersal species that is found as a single individual over sandy and muddy bottoms at depths up to 183 m (600 feet). The juveniles are found in estuaries. They reach a maximum length of 45 cm (18 inches). They are nighttime predators that consume crabs, shrimp and other invertebrates. Reproduction is oviparous with external fertilization. The Bighead Searobin is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Bighead Searobin is a resident of Mexican waters of the Atlantic Ocean being found throughout the Gulf of Mexico; they are absent from along the east coast of the Yucatán Peninsula in the Caribbean.

The Bighead Searobin is very similar to and can be confused with the Barred Searobin, Prionotus martis (dark spots between dorsal spines 1 and 2 and 3 and 4; short pectoral spine), the Bigeye Searobin, Prionotus longispinosus (gray caudal fin with a dark margin), and the Bluewing Searobin, Prionotus punctatus (blue front edges of the pectoral fins).

From a conservation perspective the Bighead Searobin is currently considered to be of Least Concern with stable widely distributed populations. Although fairly large in stature, however, they are not utilized commercially and of limited interest to most.